The Charge Coupled Device (CCD) has become the preferred image sensor for visible wavelengths because of its sensitivity, low noise, wide dynamic range, and high resolution. Temperature, readout frequency, electronics, and signal processing affect CCD noise and dynamic range. A mathematical model of these effects is presented. The model uses CCD specifications, typically provided by the manufacturer at room temperature and video frequency, to predict performance at other operating conditions. CCD performance can be improved by operating at low temperatures and low readout frequencies and by the use of appropriate support electronics and signal processing. Lowering CCD temperature reduces dark shot noise, dark signal non-uniformity, and Johnson noise. Correlated double sampling compensates for reset noise. Lower readout frequencies permit lower noise-bandwidth amplifiers. Calibration can compensate for pixel non-uniformities. The CCD model developed here describes these effects to enable prediction of CCD performance as a function of operating conditions and signal processing options.

A pinned photodiode/interline CCD Detector Array is under development for the EOS/MODIS-T project. Outstanding features of the device include large pixels, spectrally optimized fill factors, and blooming protection. The detector has 30 spatial rows and 32 spectral columns. The device layout is split into two halves; each half has its own detector area, storage area, and output structure.

Development of a 2048-squared CCD for a second-generation Space Telescope instrument has produced some very encouraging devices. The first experimental lot of 10 devices have very few defects, dark currents of less than 40 electrons/pixel/hour at -80 C, readout noise levels of less than 4 electrons rms and excellent charge transfer efficiency at signal levels of less than 10 electrons.

A third-generation SAGE instrument is about to be designed as part of the NASA Earth Observational System. Previous instruments have used individual diodes as detectors. The new instrument will use a custom design CCD to dramatically enhance the study of the gas and aerosol components of the upper atmosphere. The CCD is a 3 by 400 imaging array that has a single serial register and an exposure control drain. It will be used at the focal plane of a spectrometer covering the spectral range from 288 nm to 1.02 micron.

A small visible-band sensor, built by Lincoln Laboratory, Massachusetts Institute of Technology, will be flown as part of a sensor ensemble on the Midcourse Space Experiment (MSX) satellite, an SDIO program. This sensor, as well as the other sensors on MSX, will perform above-the-horizon surveillance experiments and acquire data on targets of interest and background phenomenology. This paper discusses the Space-Based Visible (SBV) sensor, the incorporated technologies, and the surveillance experiments to be performed.

A 6-inch diameter aperture space-based visible telescope has been optimized to perform surveillance against the space background with earth albedo as a primary source of straylight. A three mirror off-axis anastigmat has been designed to cover a 1.4 degree(s) by 6.6 degree(s) field- of-view with 60 (mu) radian spatial resolution. The telescope body and optics are constructed of 6061-T6 aluminum to provide a thermally stable optical system. The optical elements are 'superfinished' to minimize scatter. Extensive baffles and stops are utilized to further reduce straylight. The telescope will be used on the Midcourse Space Experiment platform.

Two alternative approaches to reducing errors in radiometers and photometers caused by temperature variations involve temperture monitoring and temperature control. In the first method, the measurement results are interpreted using the temperature of the detector at the time of measurement. The other method is to control the temperature of the detector to a constant value. Design considerations and examples of both approaches are discussed.

Multispectral satellite data from frequencies in the visible, infrared, and microwave regions have been applied to the analysis of atmospheric conditions where no in situ data were available on the earth's surface or aloft. Atmospheric quantities diagnosed were surface temperature, surface and upper air wind, visibility, solar insolation and precipitation, and cloud cover descriptors such as percent coverage, cloud-free locations, and cloud base height. Available in situ data adjacent to the data void area were used to calibrate the satellite-derived analysis. The success of the technique was verified by application to cases where a data void was created by withholding in situ data over part of an area, and then comparing the satellite analysis with that based on the withheld data.

An overview of the signal processor for the Space-Based Visible sensor system is presented. This signal processor, based on a 20 MHz Motorola DSP56001, places significant processing power into a satellite environment. The signal processor hardware and its real-time executive and applications software are briefly described. Typical performance figures are given, based on scenes taken by a ground-based telescope and processed by prototype hardware and software.

A miniaturized, low-power parallel processor for surveillance sensor applications is under development by Space Computer Corporation under DARPA's Advanced Space Technology Program. The basic goal of this project is the reduction, by an order of magnitude or more, of processor weight, size and power consumption for space-based sensor systems. The approach described for achieving this goal is to use low-power VLSI devices which maximize throughput per watt, together with three-dimensional hybrid wafer-scale integration and packaging technology. In its prototype version, a 12-node processor will have a peak throughput greater than 1.2 GFLOPS and occupy a volume less than 15 cubic inches.

The VUE sensor gathered data from a geosynchronous orbit in five mission areas: Target Handoff, Ultraviolet Phenomenology, Satellite Attack Warning, Space Cataloging, and Backgrounds Phenomenology. Data was gathered against the earth's disk, from deep space, and in proximity to the earth limb. To get the latter data, special measures were required in sensor design, optical fabrication, contamination control, and instrument calibration. This paper discusses these measures and present an evaluation of their effectiveness based on on- orbit calibration results.

From the functional analysis of the field-widened Michelson interferometer developed by A. Girard in 1970, this paper investigates the design of a new generation of interferometer with two input and output channels, combining the advantages of a simplified optical design with highly compact geometry and enhanced system performance. The optical design is characterized as follows: direct location of the interferometer in the front-end optics' focal plane, location of the fringes outside the interferometer (thereby directly over the detector plane), and optimization capability with a relatively low aperture number. The system-level performance of an on-board imaging Fourier Transform Spectrometer (FTS) based on such an interferometer is discussed.

The imaging spectrometer is a next-generation remote sensing sensor based on imaging spectroscopy and used as an Earth Observing System (EOS). It possesses the characteristics of both an imaging system and a spectral instrument and its output is the image-spectrum data. By virtue of the modulation transfer function (MTF) the effective instantaneous field of view (EIFOV) and effective spectral resolution (ESR) can be defined. Since these two resolutions correspond to the same criterion of MTF, the imaging spectrometer is different from the common multispectral scanner and its spatial and spectral resolutions are not independent. The relationship between the two resolutions and compromise principle are discussed in this paper.

Optical interference filters were required for the Wind Imaging Interferometer (WINDII), a Canadian instrument to fly on NASA's Upper Atmosphere Research Satellite (UARS). The WINDII instrument is a Michelson interferometer which measures wind speeds and temperatures in the upper atmosphere by analyzing airglow emissions. The original perception of the optical filters as a straightforward, low-risk element of the WINDII system, and the evolution of this view into a realization of the challenge and complexity of the filter requirements, are presented. The challenges discussed include the tight manufacturing tolerances required to achieve a wide field of view simultaneously with a narrow passband, and the problem of drifting of the filter passband over time. Changes in the scientific approach in order to relax the tolerances, tilting of the filters relative to the instruments's optic axis, and manufacturing changes in order to minimize the passband drift, are described. Other innovations in the filter design are also discussed, including a filter which incorporates a correction for chromatic aberration, and a 'split' filter which has two separate passbands.

With the prospects of future Mars and lunar missions improving, the autonomous capabilities required to accomplish many of the proposed missions has been given considerable attention. As a result, it has been recognized that the sensing capability of spacecraft must be enhanced, not only for interplanetary missions, but for those in Earth orbit as well. NASA began addressing many technology development issues under the Pathfinder Program. A sensor trade-off study was performed at ERIM under two subprograms of Pathfinder: the Autonomous Lander Project, and Autonomous Rendezvous and Docking Project. This paper is based on that trade-off study, using the scenario of an autonomous landing on a planetary body and the associated autonomous rendezvous and docking operations which would precede and/or follow such a landing. Several sensor concepts are analyzed, including RF-based, laser- based, and passive optical techniques. For each concept, a brief description of the sensor operating principles is provided, and the results of a performance analysis are summarized along with performance drivers, operational constraints, and a state-of-the-art assessment.

The restoration of images acquired by viewing through refractive and scattering media, such as the atmosphere, ocean surface, and seawater, is complicated by refractive errors at the arbitrarily corrugated interface. Additional perturbations in the received image can result from scattering within the transmissive media, as well as customary systematic errors. A restoration algorithm specific to imagery distorted by refraction and multiple scattering has been presented in an earlier paper which proposed the use of laser radar (LIDAR) reflectometry to estimate the refractive surface topography. In the previous algorithm, the reduction of degradations due to multiple scattering in seawater was described in terms of inverse filtering. In this study, the authors generalize the analysis to include a variety of media and sensor configurations. Environmental and systematic errors are quantified in terms of a statistical function which may be expressed as a frequency-domain filter that can be deconvolved from the reconstructed image. Example images are presented which verify the predicted quality of restoration, as a function of resolution and error constraints.

The Infrared Atmospheric and Signature Prediction Model (IASPM) project made a complex IR signature code accessible with a user-friendly interface, in a PC environment. That work provides the basis for the Electro-optical Model for Aerial Targeting (EMAT). EMAT will consist of an X-Window graphical user interface (GUI) controlling a diverse suite of model codes in a UNIX environment. Model codes include air and surface targets, atmospheres, backgrounds, and sensor models in the IR, visible, and UV domains. In addition to controlling the models the interface features many graphical and textual analysis features, as well as image processing capabilities. Hypertext and AI techniques are utilized to help the analyst along with the general ease of use afforded by the interface. Database capabilities help the analyst organize both input and output data. CAD interfaces are provided to assist in the integration of target objects. The EMAT software is highly portable and available for a range of workstation platforms.

In the analysis of data from spaceborne sensors, the problem frequently arises of determining the best estimate to a continuous spectrum based on a set of noisy data samples taken with broad, overlapping response functions. Examples of such data sets are the data from a retarding potential analyzer (RPA), or a set of line intensities from a solar x-ray spectrum which are to be used to estimate the Differential Emission Measure (DEM). Various approaches often suffer from such difficulties as ill-conditioned matrices, spurious structure, and non-physical negative values in the solution. This paper presents results from a smoothing spline approach, in which the spectrum is expanded in a space of cubic B-spline functions and the coefficients of the expansion are determined by regularization. The technique is first applied to model data which incorporate the general features of the RPA and DEM problems. An example is then given of a fit to data from the Retarding Ion Mass Spectrograph (RIMS) on the Dynamics Explorer 1 (DE-1) satellite.

SADARM, Sense and Destroy Armor, is an indirect fire-and-forget submunition in full-scale development at Aerojet Electronics Systems Division under contract with the U.S. Army Armament, Research, Development and Engineering Center, Dover, New Jersey. The submunition is delivered to the target area by a 155 mm Howitzer or a MLRS carrier where it is expelled and descends in a spiral spin pattern. It uses several sensors to detect armor and fires an explosively formed penetrator to defeat it. The system must operate throughout the world, perform in adverse weather, and deal with countermeasures without alteration to its aerodynamic, sensing or delivery mechanisms. This paper presents an unclassified overview of the operation of the SADARM system, its design and capability.

In today's high threat arena of air combat, the need to fly low, penetrate enemy defenses, strike effectively, and safely return to base is more valid than ever. The F-15E is designed to accomplish just that type of mission scenario, regardless of weather and time of day. In order to accomplish this demanding profile, any such aircraft requires terrain-following equipment and precision target designation. The LANTIRN system on the F-15E is designed to fulfill that role. This paper examines the two major aspects of the LANTIRN system found on the F-15E: the Navigation Pod and the Targeting Pod, and investigates flight test issues during F-15E integration testing. The Navigation Pod consists of two major subsystems, the Fixed Imaging Navigation Sensor (FINS) and the terrain following radar (TFR). Discussion of the FINS centers around the integration issues of the system and its utility in the night low level environment, as determined through flight test. In providing a 'window on the world,' this aspect of the LANTIRN system provides unique capabilities in navigation as well as weapons delivery. The TFR, the other major subsystem, is a continuation of the F-111 and RF-4 terrain following systems. While an effective system, integration of the TFR into the F-15E has been a challenge to the flight test community, with many lessons to be learned. The Targeting Pod is the second component of the LANTIRN system. Its purpose is to acquire and designate a target through use of its selectable dual field of view infrared sensor and laser ranger/designator. The laser also provides terminal guidance capability for precision guided weapons. Integration of the Targeting Pod into the avionics suite of the F-15E has provided classic examples of systems flight testing, evaluating both the technical and performance aspects of the pod, as well as the key human factors interface. The overall intent of this paper is to describe avionics testing, as applied to low level navigation and targeting systems, and to discuss lessons learned in that process, both of a specific and a general nature.

The motion of an imaging sensor causes each imaged point of the scene to correspondingly describe a time trajectory on the image plane. The trajectories of all imaged points are reminiscent of a flow (e.g., of liquid) which is the source of the term 'optical flow'. Optical-flow ranging is a method by which the stream of two-dimensional images obtained from a forward-looking forward-moving passive sensor is used to compute depth (or range) to points in the field of view. Another well-known ranging method consists of triangulation based on stereo images obtained from at least two stationary sensors. In this paper we analyze the potential accuracies of a combined optical flow and stereo passive-ranging system in the context of helicopter nap-of-the-earth obstacle avoidance. The Cramer-Rao lower bound is developed for the combined system under the assumption of an unknown angular bias error common to both cameras of a stereo pair. It is shown that the depth accuracy degradations caused by a bias error is negligible for a combined optical-flow and stereo system as compared to a monocular optical-flow system.

This paper describes a method for classifying targets -- especially helicopters -- by evaluating their vibration signatures. The mechanical vibrations of the targets are mainly caused by all movements of engines, turbines, gears, etc. Different types of targets have different vibration spectra which were measured in field trials by an experimental coherent laser radar. The measured signals show the type characteristic vibration signatures. The signatures can be evaluated by mathematic algorithms. Therefore classification of noncooperative targets is feasible.

NIRATAM (the NATO Infrared Air Target Model) was developed by the NATO AC 243, Panel IV, Research Study Group 6 (RSG-6). RSG-6 is composed of representatives from Denmark, France, Germany, Italy, the Netherlands, the United Kingdom, the United States of America, and Canada (as an observer). NIRATAM is based on theoretical studies, field measurements, and infrared data analysis performed over many years. The model encompasses all the major signature components required to simulate the infrared signature of an aircraft and the atmosphere. The vehicle fuselage, facet, model includes radiation due to aerodynamic heating, internal heat sources, reflected sky, earth, and solar radiation. Plume combustion gas emissions are calculated for H2O, CO2, CO, and other gases as well as solid particles. Lowtran 7 is used for the atmospheric transmission and radiance. The software generates graphical outputs of the target wireframe, plume flowfield, atmospheric transmission, total signature, and plume signature. Imagery data can be used for system development and evaluation. NIRATAM can be used for many applications such as measurement planning, data analysis, systems design, and aircraft development. Ontar has agreed to assist the RSG-6 by being the NIRATAM distribution center in the United States for users approved by the national representatives. Arrangements have also been made to distribute a user-friendly NIRATAM interface. This paper describes the model, presents results, makes comparisons with measured field data, and describes the availability and procedure for obtaining the software.

The authors have developed an optical delay tester based on electro-optic sampling, and designed a prototype to test the timing of high-speed IC chips. The device puts an electro-optic crystal in contact with the terminals to be tested and measures the voltage waveform applied to the crystal. Measurement precision is 100 mV or better and timing precision measurement is 50 ps.

This paper describes the capabilities and applications of inexpensive satellite platforms capable of carrying dedicated sensor packages into low earth orbit on primary or shared launch services. These satellites permit achievement of rapid operational status by employing standard buses with fixed options for orbit and power. The satellites may be configured for experimental or operational missions with lifetimes up to several years. Low cost satellites can satisfy a range of mission requirements in the areas of surveillance, drug interdiction, environmental and geophysical observations, immigration control, fisheries law enforcement, remote sensing, real-time communications, store-and-forward communications, and technology testing. These satellites may be equipped for location determination missions with ID and homing transponders and tagged objects or persons. The satellites' size, power, and weight budgets are appropriately rated for the types of dedicated mission scenarios noted above. For applications requiring continuous visibility or high availability, constellations of satellites may be both appropriate and cost-effective. Orbital parameters are determined by the launch vehicle and the requirements of the primary payload. Geographical service areas are determined by the orbital footprint, the parameters of which are determined by the mission requirements and the selection of launch vehicle. The satellites' small size permits their launch on any of several launch vehicles in domestic or international inventory. Integral to each satellite is a communications and control package which, when coupled with companion low cost earth terminals, provides programmable mission scenarios under operator control. These satellites permit rapid implementation of operational systems within tight fiscal constraints.

The need for airborne platforms to perform surveillance and communications missions over long time periods has led to a renewed interest in the utility of lighter-than-air (LTA) vehicles. Airships incorporating new technology and designs can outperform aircraft and tethered aerostats in certain law enforcement applications.

This paper discusses the development and measured performance of a high-density infrared staring camera operating with outstanding performance over the entire 3-5 micrometers band. The camera has demonstrated excellent night and thermal vision in a multitude of conditions including penetration through weather and over water. Hybrid focal plane technology was used to construct the 256 X 256 area array. Backside illuminated Indium Antimonide detectors are interconnected using Indium bumps to an advanced CMOS readout integrated circuit. The hybrid format yields high detector fill factor (>90%) and quantum efficiency (>50%). This approach has resulted in an infrared focal plane which has greater than 95dB dynamic range and is background limited (BLIP) for most applications. The paper also covers the integration of the device into a small low power cryogenic dewar as well as the interface and video electronics used to provide remarkable infrared image quality.

A precise airborne temperature-sensing technology to detect buried objects for use by law enforcement is developed. Demonstrations have imaged the sites of buried foundations, walls and trenches; mapped underground waterways and aquifers; and been used to locate underground military objects. The methodology is incorporated in a commercially available, high signal-to-noise, dual-band infrared scanner with real-time, 12-bit digital image processing software and display. The method creates color-coded images based on surface temperature variations of 0.2 degree(s)C. Unlike other less-sensitive methods, it maps true (corrected) temperatures by removing the (decoupled) surface emissivity mask equivalent to 1 degree(s)C or 2 degree(s)C; this mask hinders interpretation of apparent (blackbody) temperatures. Once removed, it is possible to identify surface temperature patterns from small diffusivity changes at buried object sites which heat and cool differently from their surroundings. Objects made of different materials and buried at different depths are identified by their unique spectral, spatial, thermal, temporal, emissivity and diffusivity signatures. The authors have successfully located the sites of buried (inert) simulated land mines 0.1 to 0.2 m deep; sod-covered rock pathways alongside dry ditches, deeper than 0.2 m; pavement covered burial trenches and cemetery structures as deep as 0.8 m; and aquifers more than 6 m and less than 60 m deep. The technology could be adapted for drug interdiction and pollution control. For the former, buried tunnels, underground structures built beneath typical surface structures, roof-tops disguised by jungle canopies, and covered containers used for contraband would be located. For the latter, buried waste containers, sludge migration pathways from faulty containers, and the juxtaposition of groundwater channels, if present, nearby, would be depicted. The precise airborne temperature-sensing technology has a promising potential to detect underground epicenters of smuggling and pollution.

The application of backscatter absorption gas imaging (BAGI) to the detection of gaseous chemical species associated with the production of illegal drugs is considered. BAGI is a gas visualization technique that allows the imaging of over 70 organic vapors at minimum concentrations of a few to several hundred ppm-m. Present BAGI capabilities at Lawrence Livermore National Laboratory and Laser Imaging Systems are discussed. Eighteen different species of interest in drug-law enforcement are identified as being detectable by BAGI. The chemical remote sensing needs of law enforcement officials are described, and the use of BAGI in meeting some of these needs is outlined.

On April 12, 1990, an international agreement between the United States, Canada, and Japan was signed that, among other things, requires real-time automatic satellite position fixing devices (transmitters) to be deployed on 100% of the Japanese squid and large-mesh driftnet fishing vessels operating in the North Pacific in 1990. These transmitters must allow automatic, real-time monitoring of the location and identity of each vessel by Japanese, Canadian, and U.S. officials. Japan had approximately 350 vessels conducting driftnet operations in the North Pacific Ocean in 1990. Similar agreements were reached between the U.S. and Korea and the U.S. and Taiwan in 1989. Taiwan agreed to equip 100% of its 135 North Pacific driftnet vessels with transmitters in 1990. South Korea agreed to equip 100% of its 188 driftnet vessels with transmitters in 1990. All countries agreed to fund the purchase, installation, maintenance, and data processing costs involved in this program. All countries agreed to provide U.S. authorities with real-time access to the satellite-generated position data. In July 1990, U.S. officials began monitoring the locations of approximately 700 foreign driftnet vessels operating in the North Pacific. Tests were conducted of two position fixing transmitter systems using National Oceanic and Atmospheric Administration (NOAA) satellites while the negotiations, which took over two years to complete, were ongoing. An overview of the systems tested and the results of those tests were provided to Japan, Taiwan, and Korea to assist them in choosing a transmitter best suited to their program requirements. Each country chose to use the Argos Location and Data Collection Satellite System. The Argos system is packaged on a NOAA Tiros-N satellite. This paper describes the need for a foreign fishing vessel tracking system, the results of the satellite transmitter test program, and the successful implementation of this program in 1990.

The Wedge Imaging Spectrometer (WIS) represents a novel implementation of an imaging spectrometer sensor that is compact and rugged and, therefore, suitable for use in drug interdiction and pollution monitoring activities. With performance characteristics equal to comparable conventional imaging spectrometers, it would be capable of detecting and identifying primary and secondary indicators of drug activities and pollution events. In the design, a linear wedge filter is mated to an area array of detectors to achieve two-dimensional sampling of the combined spatial/spectral information passed by the filter. As a result, the need for complex and delicate fore optics is avoided, and the size and weight of the instrument are approximately 50% that of comparable sensors. Spectral bandwidths can be controlled to provide relatively narrow individual bandwidths over a broad spectrum, including all visible and infrared wavelengths. This sensor concept has been under development at the Hughes Aircraft Co. Santa Barbara Research Center (SBRC), and hardware exists in the form of a brassboard prototype. This prototype provides 64 spectral bands over the visible and near infrared region (0.4 to 1.0 micrometers ). Implementation issues have been examined, and plans have been formulated for packaging the sensor into a test-bed aircraft for demonstration of capabilities. Two specific areas of utility to the drug interdiction problem are isolated: (1) detection and classification of narcotic crop growth areas and (2) identification of coca processing sites, cued by the results of broad-area survey and collateral information. Vegetation stress and change-detection processing may also be useful in detecting active from dormant airfields. For pollution monitoring, a WIS sensor could provide data with fine spectral and spatial resolution over suspect areas. On-board or ground processing of the data would isolate the presence of polluting effluents, effects on vegetation caused by airborne or other pollutants, or anomalous ground conditions indicative of buried or dumped toxic materials.

Airborne lidar measurements have been conducted for a variety of research applications over the past 10 years. These efforts have demonstrated the value of operating laser-based remote- sensing instrumentation from airborne platforms for mapping of atmospheric distributions of particulate and gaseous constituents over regional areas with high spatial and temporal resolution. While most of the investigations have been directed to the observation of effluents injected into the atmosphere from industrial sources or of tracer material released into the atmosphere for evaluation of transport and diffusion processes, the techniques used may have applications to detection and surveillance for law-enforcement purposes. Data examples are presented that illustrate airborne lidar elastic scattering, fluorescent scattering, and differential absorption measurements of atmospheric targets.

A proof of concept test has been completed that demonstrates the potential utility of the Applied Analysis Spectral Analytical Process (AASAP) for remote spectral fingerprinting of objects of law enforcement interest. The test was directed toward demonstrating feasibility of a proposed VSIS (Vehicle Signature Identification System) for drug interdiction applications. VSIS will measure reflected light spectra of vehicles at strategic locations, such as border crossings. AASAP will be used by VSIS to automatically extract the vehicle signature, which is based on diagnostic spectral fine structure in the spectrum of the vehicle coating. The extracted signature will be automatically compared to a library of one or more stored signatures for specific vehicles of interest to determine whether or not the subject vehicle is one of those vehicles of interest. The proof of concept test was conducted using a boom- mounted 63 channel sensor (0.5 - 2.5 micrometers ) operated by MTL Systems, Inc. Spectra of 18 automobiles (3 cars each from 6 color groups) were measured in April, 1990. Spectra from two locations on the roof of each car were measured. The signatures for each of the 18 vehicles were distinct, while the two spectra for each vehicle were nearly identical. Phase II of the test involved remeasuring the spectra four months later and comparing the results to the Phase I signatures. The Phase II test measured six vehicles, one from each color group, and the signatures for those vehicles were stable. The test demonstrated that AASAP is highly discriminating and robust as vehicle fingerprinting tool. While the test was directed toward drug interdiction applications, the results suggest that VSIS-like systems employing AASAP may have broad law enforcement application potentials.

A portable ultraviolet device that uses imaging of ultraviolet laser induced fluorescence has been developed which has the capability of detecting concealed substances to a range of 30 meters. The system also has the potential for near real time tracking, surveillance, and identification of suspect targets.

Several simple, low-cost algorithms have been explored for use in the enhancement of imagery produced by uncooled focal plane arrays (UFPA). These algorithms address the main problems that UFPA-produced imagery typically demonstrate. In addition to enhancing UFPA-produced imagery, all these algorithms are simple and allow for inexpensive hardware implementation.

The problem of conducting surveillance and detection of aircraft, boats, and vehicles bringing contraband into remote areas of the United States has changed dramatically within the past 20 years. This dramatic change resulted from the evolutionary adaptation of advanced technology to perform the surveillance and detection role. Unlike the predecessor ground-based radars deployed along the CONUS in the mid-1970s, the aerostat radar systems are effective in the detection of low-flying aircraft in mountainous areas where ground clutter formerly prevented low-altitude target detection. While showing promise, the early aerostat systems lacked the sophistication necessary to provide the surveillance capability required during all operating conditions. Land and sea clutter returns often masked the small radar cross-section targets of interest. During the 1980 time period, new signal processing technology offered a solution to the problems identified during early aerostat operations. New performance requirements were formulated, resulting in the development and deployment of the tethered aerostat radar systems along the southern border of the United States and at specific sites in the Caribbean. Testing of the new generation aerostats was conducted using techniques to be discussed in this paper. Testing revealed that, while many of the problems that limited the usefulness of the earlier aerostat radars have been solved, more subtle problems existed. These problems have been identified, and solutions are being implemented. In addition, there are marine and land surveillance applications for the tethered aerostat radar system that have been studied, and potential improvements could be incorporated for the future detection and tracking of marine and vehicular traffic.